我继承了BackgroundWorker并重写了OnDoWork：

protected override void OnDoWork(DoWorkEventArgs e)
{
    WorkerEndedEvent.Reset();
    base.OnDoWork(e);
}

我的问题是,它将从哪个线程调用？是否可以确保在我调用RunWorkerAsync()时调用它,还是可以在以后调用它(即从工作线程中调用)？

解决方法:

它将由工作线程调用,并且不能保证在调用RunWorkerAsync期间被调用.

RunWorkerAsync的文档指出：

The RunWorkerAsync method submits a request to start the operation
running asynchronously. When the request is serviced, the DoWork event
is raised, which in turn starts execution of your background
operation.

因此RunWorkerAsync仅提交启动操作的请求-这将引发DoWork事件.它不能保证何时调用DoWork.

它也是documented,因为它使用单独的线程来工作：

Executes an operation on a separate thread.

因此很明显,在不同于RunWorkerAsync调用的线程上调用DoWork.